var intervalID;
var secs;	
secs = 10;

function timer() {
	intervalID = setInterval(changeTable, secs*1000);
}

function changeTable() {
	var elem1 = document.getElementById("tabella1");
	var elem2 = document.getElementById("tabella2");
	if(elem1.className != "hide") {elem1.className = "hide"; } else {elem1.className = "show"; }
	if(elem2.className != "hide") {elem2.className = "hide"; } else {elem2.className = "show"; }
}